In a world of increased travel restrictions, we tend to think that the need for free movement is something new. This is why the International Regulations on the Admission and Expulsion of Aliens proposed in 1892 by the Institute of International Law came as a big surprise to me. Here is why:

ARTICLE 6. Free entrance of aliens to the territory of a civilized state, may not be generally and permanently forbidden except in the public interest and for very serious reasons, for example, because of a dangerous organization or gathering of aliens who come in great numbers.

ARTICLE 7. The protection of national labor is not, in itself, a sufficient reason for non admissions.

How far along did policy and regulations progress since then?

citation from Juss, S.S. (2006), International Migration and Global Justice, Ashgate Publishing Limited: Hampshire, p.3